Surfaces of decreased water wettability and process for the preparation thereof



March 28, 1961 YUN JEN 2,977,245

SURFACES OF DECREASED WATER WETTABILITY AND PROCESS FOR THE PREPARATION THEREOF Filed June 24, 1957 CONTACT SURFACE WlTH SOLUTION OF CATIONIC POLYAMINE HAVING A MOLECULAR WEIGHT ABOVE [0,000 AND CONTAINING AT LEAST ONE REACTIVE AMINO GROUP FOR EVERY IO CARBON ATOMS THEREIN l I WASH TO REMOVE UNADSORBED I I POLYAMINE CONTACT SURFACE WITH DILUTE AQUEOUS SOLUTION OF A SOAP HAVING A HYDROPHOBIG ANION V WASH TO REMOVE EXCESS SOAP DRY INVENTOR.

YUN JEN ATTORNEY United States Patent SURFACES OF DECREASED WATER WETTABIL- ITY AND PROCESS FOR THE PREPARATION THEREOF Yun Jen, Stamford, Conn., assignor to American Cyanamid Company, New York, N.Y., a corporation of Maine 1 Filed June 24, 1957, Ser. No. 667,700

19 Claims. (Cl. 117-72) The present invention relates to a process for treating of the treating solutions or by brushing, spraying or hydrophilic surfaces to decrease their wettability by water and to the novel surfaces thereby produced.

It is known that hydrophilic surfaces may be rendered water-repellent by contacting the surfaces with a dilute aqueous solution of certain long chain aliphatic amine salts such as octadecylamine hydrochloride so as to form an amine coating thereover, as disclosed in U.S. Patent No. 2,356,542, granted to C. K. Sloan on August 22, 1944. According to the patent the amines form a coating over the hydrophilic surfaces causing them to become hydrophobic. The process of the patent has two major disadvantages.

(l) The coating is non-durable in that it is substantially completely removed when the treated surface is washed with soap and water.

(2) The water-repellence is fugitive in that the effect largely disappears Within a few months. 7

The discovery has now been made that hydrophilic surfaces can be treated to decrease their wettability by Water by a process which comprises two principalsteps. In the first step, the surface is contacted with a dilute aqueous solution of a cationic high molecular weight amine polymer as hereinafter more particularly described, whereby at least some of the polyamine is irreversibly adsorbed by the surface. In the second step, the surface is contacted with sufiicient of a dilute aqueous solution of a soap having a hydrophobic anion to convert at least some of the adsorbed polyamine to hydrophobic soap form. Thereafter the surface may be dried. By this process it is readily feasible to form sufficient hydrophobic polyamine soap on the surface to render the surface strongly water-repellent, as if oiled. Surprisingly, the bond between the adsorbed hydrophobic polyamine soap and the surface is so strong that polyamine soap is removed only to a negligible extent when the surface is flushed with water. Even more surprisingly, washing with soap and water generally increases the water repellence of the surface.

In the process, the amount of water-repellence developed and the luster of the surfaces are improved by flushing the surface with plain water after each treatment so as to remove any unadsorbed polyamine which may be present before the surface is contacted with the dilute aqueous soap solution and to remove any excess soap solution before the surface is allowed to dry.

From the foregoing it will be seen that the product of the present invention is a surface which is rendered water-repellent by the presence thereon of irreversibly adsorbed hydrophobic polyamine soap. Our evidence indicates that maximum water-repellence I is achieved when the polyamine soap is present in amount approximately equivalent to a monomolecular layer. However, the invention includes surfaces on which a substantially smaller amount of polyamine soap is present.

The invention does not depend upon the particular surface treated. Very satisfactory results have been obtained in the case of Portland cement, glass and brick;

rolling therewith. In most instances, only sufiicient contact time with the polyamine solution is needed to cause at least some of the polyamine to be adsorbed as base for the soap, and in the case of the secondstep for atleast some of the adsorbed polyamine to be converted to hydrophobic soap form. Longer contact times-give greater water-repellence, best results being obtained when the hydrophilic surface is contacted with polyamine solution until the adsorptive capacity therefor is substantially satisfied and when the application of soap solution is continued until formation of polyamine soap substantially ceases. Both steps proceed rapidly, and in practice, there is little advantage in allowing more than about 5 minutes for either Very satisfactory results have been obtained with contact times of less than one minute.

The polyamines employed in the present invention have average molecular weights in excess of about 10,000. When the molecular weight of the polymer is materially less, the Water-repellence imparted by the treatment is fugitive, the coating being more or less readily washed away and being subject to absorption into the substrate with passage of time. Furthermore, the polyamines contain at least one amino nitrogen atom having at least one ionizable or replaceable hydrogen atom for every 10 carbon atoms in the molecule, as it I is through such atoms that the molecule as a whole is anchored tothe substrate and to which the hydrophobic soap anions are attached. Substantially better results are obtained when this ratio is increased to 1:5 and better results still when the ratio is increased to 1:2 as in the case of polyethylenimine or polyvinylamine.

The invention does not depend upon the concentration of either the polyamine or the soap in the two treat-V ing solutions employed. Satisfactory resultshave, been obtained when both have been employed at concentrations as low as 0.01% and the evidence is thus that more dilute solutions yield useful results. The invention does not depend upon the adsorption of any particular amount of polyamine during treatment. The e'vidence is that not even a complete monomolecular layer is needed-to pro-1 vide sufficient polyamine as base for at least a significant amount of soaps. In particular instances optimum conditions of treatment are conveniently found by trial as illustrated in the examples. i

The polyamine solutions appear to be most advan-' tageously applied at about neutrality (pH 6-8) but good ylenimine or C-methylethylenimine.

results have been obtained over the range pH 4-10. The soap solutions are likewise advantageously applied at about neutrality and in general may be applied within.

the pH range in which they are stable.

A large number of synthetic polyamine condensation products are known which can be used as primary treating agents in the process of the present invention. They may be essentially linear as in the case of the carbonnitrogen chains formed by homopolymerization of eth- Similar materials maybe prepared by condensing an alkylenediamine with an alkylenedichloride. Preferably the alkylenediamine and alkylenedichloride are selected so that the total number of the linear chain carbon atoms included .by/the diamine groups of the alkylenediamine plus the linear chain carbon included by the chlorine atoms of the alkylenedichloride is between about 5 and 9V-inclusive. Useful products thus may be prepared by condensing 1,2-propanediamine with 1,3-dichloropropane wherein thetotal number of included carbon atoms is 5, or by condensing trimethylenedia'mine with 1,3-dichloropropane wherein the total number of included carbon atoms is 6. Alternatively, a polyalkylenepolyamine may be employed in place of the alkylenediamine and thus triethylenetetramine may be reacted with 1,3-dich1oropropane to form suitable high molecular weight polyalkylenepolyamines.

A further type of polyalkylenepolyamine may be employed by reacting a divinyl compound with diamine. Thus methylenebis'acrylamide may be reacted with 3,3- iminobispropylamine. A third group of condensation products may be prepared by reacting a polyalkylenepolyamine with epichlorohydrin or a lower dichlorohydrin to form a high molecular weight water-soluble crosslinked (i.e., reticulated) polyamine containing substantially all the nitrogen atoms in secondary form. Similar condensation products are prepared by reacting ammonia with epichlorohydrin or similar halohydrins in aqueous solution.

Furthermore, there may be employed polyamines con- 5 ethylamine.

4 of ethylenediamine (0.2 mol) and 63.8 gm. of water with stirring at 70 C. for several minutes until the syrup became very viscous and appeared close to gelation. The reaction was then halted by addition of 3.7 gm. of di- The product had the following theoretical structure In the product there were two amino nitrogen atoms having one ionizable hydrogen atom each for every 13 linear chain atoms.

(2) Methylenebisacrylamide triethylenetetramine (MBA-TETA) condensate. The procedure for polyamine 15 No. 1 was repeated except that 29.6 gm. (0.2 mol) of trisisting principally of straight or branched carbon chains carrying amino groups as in the case of polyvinylamine. Similarly, polymeric amines obtained by hydrogenation of polyacrylonitrile may be employed. Still another group of polyamine that may be useful is the ammonia reaction product of an ethylene-carbon monoxide copolymer [J.A.C.S. 76, 6394 (1954)].

In the polyamines some of the nitrogen atoms may be in tertiary form. Methylol groups are particularly advantageous for the purposes as they permit the polyamine to increase molecular size after application, and may be introduced by reacting the polymers with formaldehyde so as to produce a condensation product which nevertheless contains secondary nitrogen atoms within the range stated. That is, after reaction with the formaldehyde and before application to the surface, the polyamine should contain not substantially less than one secondary amino nitrogen atom for every 10 carbon atoms present.

As soaps for use in thetreating solution there may be used any salt of a hydrophobic substantially water insoluble organic acid which is soluble in water sufiiciently to permit a 0.01%1% aqueous treating solution to be formed. Suitable organic acids normally contain more than 12 carbon atoms and include stearic, oleic, palmitic, linoleic, linolenic, and dehydroxylated ricinoleic and acid mixtures such as coconut fatty acids, fish oil fatty acids and the high molecular weight acids obtained by controlled oxidation of petroleum. Rosin and maleated rosin may be used. Acids containing conjugated double bonds are advantageous in that they tend to polymerize on the surface through these bonds thereby becoming more water-repellent.

The foregoing acids may be saponified by use of any base yielding a water-soluble soap including sodium, potassium and ammonium hydroxides, dimethylamine, and morpholine.

The invention is illustrated in the flowsheet, which shows the principal process steps involved and their sequence. Either or both of the washing steps may be omitted, as shown by the dotted lines.

The invention will be further illustrated by the examples which follow. These examples represent embodiments of the invention and are not to be construed as limitations thereon. Parts are by weight unless otherwise stated.

PREPARATION OF POLYAMINES The following illustrates the preparation of high molecular weight water-soluble cationic linear polyamines suitable for use in the process of the present invention.

(1) Methylenebisacrylamide ethylenediamine (MBA- ED) condensate. This material was prepared by heating 30.8 gm. of methylenebisacrylamide (0.2 mol), 17.4 gm.

60 97% NaOH in 150 gm.-of water.

75 hydrophilic substrate surfaces.

and thus contained four linear nitrogen atoms having one ionizable hydrogen atom each for every 19 chain atoms.

25 (3) Methylenebisacrylamide-triethylenetetraminetorrnaldehyde (MBA-TETA-Cl-l O) condensate. The procedure for the preparation of the polyamine No. 2 was repeated after which 12.3 gm. (0.3 mol) of 37% aqueous formalin solution was added 10 minutes after the diethylamine had been added. The formalin was then reacted at elevated temperature for 15 minutes.

(4) Polyethylenimine (PEI). The sample had a Gardner-Holdt viscosity of E at 33% solids in water and contained substantially more than 200 --NHCH CH groups per molecule.

(5) Iminobispropylamine ethylenedichloride (IBPA- ED) condensate; This condensate was formed by reacting 31-7 gm. of ethylenedichloride and 53.1 gm. of 3,3- iminobispropylamine in 20.2 parts of water at reflux until a condensate was obtained which, after dilution with 81.2 gm. of water, had a Gardner-Holdt viscosity at 25 C. of at least B. The product was largely composed of the recurring linkage groups.

(6) Tetraethylenepentamine dichlorohydrin (TEPA- DCI-I) condensate. To a solution of 94.5 gm. (0.5 mol) of tetraethylenepentamine in 492 gm. of water was slowly added with agitation 161.2 gm. (1.25 mols) of dichlorohydrin (1,3-dichloro-2-propanol), a temperature of 10 C. being maintained. There was then added 51.5 gm. of

The mixture was agitated forthreehous. The condensate was used when in a state of high viscosity while yet in hydrophilic ungelled form and was highly cross-linked.

(7) Polyvinylamine (PVA) This material having the 55 theoretical structure was prepared by the method shown in Journal of the Examples 1-7 The following illustrates the formation of an adsorbed hydrophobic polyamine soap layer on several typical The substrate materials employed were siliceous (glass, concrete, brick), cellulosic (cotton shirting and pater), and lignin (wood).

Each sample was treated by immersion (with occa; sional gentle agitation) for five minutes at room temperature in a 0.1% aqueous solution ofpolyamine agents adjusted to pH 9.0, after which the sample was rinsed for five minutes under a stream of fresh water to remove any unadsorbed polyamine present. The sample was thenimmersed for five minutes in at least 20 times its weight of 0.1% aqueous sodium stearate solution at room temperature, rinsed again, and allowed to dry at room temperature. 3

The samples were tested by tilting to an angle of 45 and allowing a slow stream of water to flow thereover for about a minute. During the test the tendency of the droplets (into which the stream broke) to adhere to the surface was noted. A rating of l was given to denote substantially complete water-repellence with substantially no wetting (as if the surface had been oiled). A rating of 2 was given to denote good initial water 'repellence with development of slight subsequent wetting, and a rating of 3 to denote a substantial terminal absence of water-repellence. A rating of l or 2 was regarded as satisfactory.

Results are as follows.

Polyamine Water Repellence Name Glass Brick Wood Cloth and -CH2CH- Example 8 The following illustrates the application of the method of the present invention to large structural hydrophilic surfaces. For this illustration the substrates selected were two automobile bodies which respectively had baked enamel and nitrocellulose lacquer finishes which had become hydrophilic as the result of several years of weathering.

The bodies were washed with warm soapy Water to remove grime and then were thoroughly flushed with fresh water to remove all residual soap. The surfaces were then sponged while wet for five minutes with a 0.5% aqueous solution of polyethylenimine, after which the bodies were again thoroughly flushed with water to re move any unadsorbed polyethylenimine present. While Paper still wet, the bodies were sponged for several minutes with a 0.5% aqueous solution of a commercial soap detergent, having as its active ingredients a mixture of the sodium salts of higher aryl sulfonates and higher alkyl sulfates, after which excess detergent solution flushed off.

When dry, the bodies were highly hydrophobic and shed water as if they had been oiled.

Example 9 A porcelain enamel bathtub was thoroughly washed with dilute caustic solution and water and then sponged for a few minutes with a 0.25% aqueous solution of ethylenedichloride-iminobispropylamine condensate. Excess (unadsorbed) amine was then flushed off with fresh water and the bathtub sponged for a few minutes with a dilute aqueous solution of a commercial hand soap. Excess soap solution was then flushed off. The bathtub became very hydrophobic, and it was noted that its tendency to accumulate scum. during use decreased substantially. P

I claim:

1. A process of treating a hydrophilic surface to decrease its wettability by water, which comprises contacting said surface with a dilute aqueous solution of a high molecular weight cationic polyamine having an-average molecular weight in excess of 10,000 and containing at least one amino nitrogen atom having at least one replaceable hydrogen atom for every 10 carbon atoms therein, thereby irreversibly adsorbing at least some of said polyamine on said surface, and then contacting said surface with suflicient of a dilute aqueous solution of a soap having a hydrophobic anion to convent said adsorbed polyamine to hydrophobic soap form.

2. A process according to claim 1 wherein the surface is concrete. I 7

3. A process according to claim 1 whereinthe, surface is glass.

4. A process according to claim 1 wherein the surface is a weathered hydrophilic baked pigmented alkyd resin film.

5. A process according to claim -l wherein the surface is cellulose.

6. A process according to claim 5 wherein the surface is paper.

7. A process according to claim 1 wherein the surface is wood.

8. A process according to claim 1 wherein the polyamine is polyethylenimine.

9. A process according to claim 1 wherein the polyamine is a methylene bisacrylamide-polyalkylenepolyamine condensate.

10. A process according to claim 1 wherein the polyamine is a polyalkylenepolyamine-epichlorohydrin condensate.

11. A process according to claim 1 wherein the surface is contacted with polyamine solution until the adsorptive capacity of the surface for said polyamine is substantially satisfied.

12. A process according to claim 1 wherein after ad sorption of the polyamine and before contact of the soap solution the surface is washed with water to remove any unadsorbed polyamine present.

13. A process according to claim 1 wherein the soap having a hydrophobic anion is sodium stearate- 14. A process according to claim 1 wherein the surface is contacted with the dilute aqueous soap solution until formation of polyamine soap has substantially ceased.

15. A process of rendering a surface water-repellent which comprises contacting said surface with an aqueous solution containing 0.01%1% by weight of a high molecular weight cationic linear chain polyamine having an average molecular weight in excess of 10,000 and containing at least one amino nitrogen atom having at least one replaceable hydrogen atom for every ten carbon atoms therein, until the adsorptive capacity of said surface for said polyamine is substantially satisfied, washing said surface to remove any unadsorbed polyamine present, and then contacting said washed surface with sufficient of a dilute aqueous solution of a soap having a hydrophobic anion to convert said adsorbed polyamine to.

carbon atoms therein, until 'tthe adsorptive capacity of said surface for said polyamine is substantially satisfied, washing said surface with water to remove any unadsorbed polyarnine present, then contacting said Washed surface with sufiicient of a dilute aqueous solution of a soap having a hydrophobic anion to convert said adsorbed polyarnine to hydrophobic soap form, and drying said surface.

17. A normally hydrophilic surface of decreased wet tability by Water resulting from the presence thereon in adsorbed form of a polyamine soap formed by interaction of a normally water-soluble polyamine having an average molecular Weight in excess of 10,000 and containing at least one amino nitrogen atom having at least one replaceable hydrogen atom for every 10 carbon atoms therein, with a water-soluble soap having a hydrophobic anion.

18. A surface according to claim '17 having adsorbed thereon said adsorbed polyamine soap in amount approximately equivalent to a monornolecular layer.

19. A normally hydrophilic surface rendered Waterrepellent by the presence thereon of an irreversibly adsorbed small amount of a hydrophobic polyethylenimine stearate, said'polyethylenimine stearate containing at least units.

References Cited in the file of this patent UNITED STATES PATENTS 2,375,348 Cohen May 8, 1945 2,495,283 Werntz Ian. 24, 1950 2,573,956 Daniel et al Nov. 6, 1951 2,579,033 Cupery Dec. 18, 1951 2,673,824 Biefcld et al Mar. 30, 1954 2,677,681 Gill May 4, 1954 2,698,793 Landes Jan. 4, 1955 2,721,811 Dacey et a1. Oct. 25, 1955 2,729,560 House et al. Jan. 3, 1956 2,763,571 Wooding et a1 Sept. 18, 1956 2,824,861 Conbere et a1. Feb. 25, 1958 2,825,714 Melamed Mar. 4, 1958 2,884,057 Wilson et a1. Apr. 28, 1959 2,884,407 Keim Apr. 28, 1959 

1. A PROCESS OF TREATING A HYDROPHILIC SURFACE TO DECREASE ITS WETTABILITY BY WATER, WHICH COMPRISES CONTACTING SAID SURFACE WITH A DILUTE AQUEOUS SOLUTION OF A HIGH MOLECULAR WEIGHT CATIONIC POLYAMINE HAVING AN AVERAGE MOLECULAR WEIGHT IN EXCESS OF 10,000 AND CONTAINING AT MOLECULAR WEIGHT IN EXCESS OF 10,000 AND CONTAINING AT PLACEABLE HYDROGEN ATOM FOR EVERY 10 CARBON ATOMS THEREIN, THEREBY IRREVERSIBLY ADSORBING AT LEAST SOME OF SAID POLYAMINE ON SAID SURFACE, AND THEN CONTACTING SAID SURFACE WITH SUFFICIENT OF A DILUTE AQUEOUS SOLUTION OF A SOAP HAVING A HYDROPHOBIC ANION TO CONVERT SAID ADSORBED POLYAMINE TO HYDROPHOBIC SOAP FORM. 